Gun-barrel.



No. 689,501. Patented Dec. 24, I90l. w. F. MABKHAM. GUN BARREL.

(Application filed Apr. 12, 1901.)

(No Model.)

A r r9 W w m w w J 4 U a NITED TATES shins.

WILLIAM Ih'MARKHAM, F PLYMOUTH, MICHIGAN.

GUN-BARREL.

SPECIFICATION forming part of Letters Patent No. 689,501, datedweoe'mber 24, 1 cos.

i Application filed April 12, 190i.-

To-a/ZZ whom, it mal concern: Be it known that I,WILLIAM F.MARKHAM, a citizen of the United States, residing atPlymouth, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Rified Gun-BarrelsQof which the following is a specification, refer, ones being had therein to the accompanying drawings.

The invention consists in a new and useful improvement in rifled gun-barrels, and particularly in a barrel consisting of a tube formed from a grooved sheet or strip of metal shaped into a tube and twisted, preferably combined with a reinforcing or inclosing tube, all as more fully hereinafter described and shown.

In thedrawings,Figure lis a plan view of the strip from which the gun-barrel'is made. Fig. 2 shows the strip provided with the grooves or channels formed upon one side thereof. Fig. 3 is a cross-section of Fig. 2. Fig. 4 isa diagram-section illustrating the manner of forming the strip into a U shape as the first step toward shaping it into its cylindrical form. Fig. 5 is a cross-section showing the dies in position to complete the cylindrical form. 'Fig. 6 is a side elevation of the chiti pleted barrel twisted to give the spiralefi'ect to'the grooves or rifiing, and Fig. 7 is a sectional perspective view of the complete barrel. In the manufacture of. my improved barrel I proceed as follows: I take a flat strip of steel or other suitable metal A (shown at Fig. 1) and by any suitable machine, such as a milling-machine, 1 form longitudinally'in it a se- 'ries of grooves B. One of these grooves B, I preferably arrange directly at the joint at one side, so that the joint when the strip is formed into a tube will be at the bottom of one of the grooves or channels. At the same time and preferably with the same tool I form thechamfered or inclined faces 0 on the edges of the strip. This strip thus shaped I then form into'a tube in any suitable manner. The way which I preferably employ is, first, by means of suitable dies Dand E form Serial No. 55,520. (No model.)

it into a U shape, as shown in Fig. 4, and then by the dies F and G, I shape it into a tube or cylinder, as shown in Fig. 5. To insure perfectwork with the dies F and G, I preferably place in' the'U-shaped blank before it is operated on by the dies F and G a cylindrical mandrel H, which is shown in position in the tube in Fig. 5; The tube thus formed will be a split'tube-that is, it will have a joint along one-side and will have running longitudinally through it a series of straight channels formed by grooves B it,

and in order to givethese a spiral turn 1 bind- 01' grasp the tube (after moving it from the dies F and G) at opposite ends and twistit to the desired extent necessary to give the spiral efiect in the channels or grooves. I then have a tube I, which exteriorly is like that shown in Fig. Sand which interiorly is provided with the spiral rifiing, as shown in Fig. 7. I then take another plain blank or strip, like A, onlywider, and benditinto U shape by dies like E and l), and then place within it as a mandrel the tube I, and then close the plain tube aboutthe tube I with a straight joint, thus forming an outer or .inclosing tubeJ around the inner tube l, as plainly shownin Fig. 7. Inasmuch as in such a rifled barrel it is not necessary to give a twist to exceed one-third of a turn it is obvious that there will be opposite the joint in the tube I an unbroken or unjointed side in the tube J',-and on this unbrokenside of the tube I; I arrange the joint K of the outer tube J, so that at no point do the two slits or joints cross each other. I then preferably solder the joint K and have formed the ride-barrel shown in Fig. 7, consisting of an inner split tube with a spiral riding and an outer inclosing split tube, the two tubes having breakjoints.

I do not desire to be limited tothe'use of an outer split tube, as it is evident that a jointless tube may be shrunk on or forced onto the inner tube, or indeed. that other means of reinforcing the inner tube may be employed. 

